As a producing process of propylene oxide, a process in which cumene hydroperoxide with propylene is reacted, is known.
In the liquid reaction mixture obtained by the reaction, water, hydrocarbons, oxygen-containing organic compounds such as methanol, propionaldehyde, acetone and methyl formate as impurities, are contained in addition to propylene oxide as a target product. Therefore, multi-stage purification steps become necessary to separate and recover propylene oxide of high purity from the liquid reaction mixture.
In purification of propylene oxide, use of a hydrocarbon as an extractant is publicly known. For example, U.S. Pat. No. 3,843,488 discloses that an alkane such as octane is effective for removing hydrocarbons having 6 carbon atoms as impurities. Further, JP 50-007571 B discloses that an alkane such as octane is effective for removal of water. Furthermore, U.S. Pat. No. 5,133,839 discloses that a hydrocarbon such as octane is effective for removal of impurities such as methanol, propionaldehyde and acetone.